Elastin is an insoluble protein found in most connective tissues in conjunction with other structural elements such as collagen and mucopolysaccharide. It is usually defined as that protein material which remains after all other connective tissue components have been removed. It is obvious that this element of connective tissue must be understood if one is to understand in full the processes of growth, development, aging, and repair in the mammalian organism and one is to understand the physiology and chemical pathology of the large blood vessels. Our laboratory has focused its attention on the chemistry and biosynthesis of the crosslinkages in elastin. Much progress has been made, but the results are far from complete. One major effort in our laboratory will be concerned with the isolation and characterization of peptides containing the unusual crosslinkages present in elastin. Another area will focus on the biosynthesis of these crosslinkages more specifically, the enzymes involved in the biosynthetic pathway and the precursor molecule, tropoelastin. These studies will include the use of tissue culture in the presence and absence of penicillamine. Most recently, it has become apparent that the crosslinkages in elastin are similar to the covalent crosslinkages in collagen. Comparative studies in this area will be pursued as well. Finally, it is our intention to study the interaction of elastin with other structural macromolecules such as collagen, glycoprotein and lipoprotein.